Photodynamic activity of chlorin e6 and chlorin e6 ethylenediamide in vitro and in vivo.

Several parameters of chlorin e6 and its derivative chlorin e6 ethylenediamide have been investigated as these compound are potential sensitizers for photodynamic therapy. A study carried out to compare the cellular uptake of the pigments indicates that chlorin e6 ethylenediamide possesses an enhanced affinity for tumour cells and cellular membranes. Comparison of the uptake in induced sarcoma shows that chlorin e6 ethylenediamide is a much better tumour localizer than chlorin e6.

The laws of delayed photohaemolysis sensitized by chlorin e6.

The relationships between the rate of post-irradiated photohaemolysis sensitized by chlorin e6 and parameters such as the light fluence (time of irradiation) and sensitizer concentration were studied. On the basis of the single-parametric approach proposed by Valenzeno and Pooler, it was found that the haemolytic rate varies with the square of both the light fluence and the sensitizer concentration. Thus it can be concluded that, in a single erythrocyte lesion, two chlorin e6 molecules participate, each absorbing one photon.

[The porphyrin content of the erythrocytes in cancer patients].

Levels of copro- and protoporphyrin in red blood cells obtained from patients with tumors of the stomach, large bowel and thyroid are discussed. The levels of both porphyrins proved markedly increased in patients with gastric and intestinal cancer but were nearly normal in cases of benign tumor of various sites and thyroid cancer.

[The use of porphyrins for assessing the effect of low doses of ionizing radiation on the human body].

Data on porphyrin metabolism disturbances under the action of ionizing radiation on the human body are presented. The studies are based on estimating the quantitative content of coproporphyrin in the diurnal urine diuresis of persons irradiated as a result of the Chernobyl accident. The results of examining the population of a number of the zones of close control in Mogilev and Gomel Provinces are considered.

Chlorin e6-liposome interaction. Investigation by the methods of fluorescence spectroscopy and inductive resonance energy transfer.

On the basis of spectral fluorescence and polarization measurements and results obtained on the luminescence quenching of the membrane fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) by incorporated chlorin e6 (chl e6) molecules, it is shown that the interaction of the water-soluble pigment with smaller unilamellar lipid vesicles occurs by a mechanism of partition between the aqueous and lipid phases (partition coefficient Kp = 6.7 x 10(3) and provides rigid fixing of chl e6 monomers at the boundary between the polar and non-polar parts of the lipid membrane. In terms of inductive resonance electronic excitation energy transfer between DPH and chl e6 (R0 = 36.

[The distribution of chlorine e6 and its derivatives in HeLa cells studied using luminescence microscopy].

The influence of the chemical structure of porphyrin pigments on their accumulation and localization in HeLa cells has been examined by the scanning fluorescence microphotometry. It has been found that the replacement of carboxyl groups of chlorine e6 for methyl and amino groups has no influence on the pigment distributions in cells. All the pigments are bound by cell membrane structures.

[Singlet oxygen and photodestruction of erythrocyte membranes, sensitized by chlorin e6].

By using scavengers of active oxygen forms (AOF) the role of 1O2, O2- and HO in photodestruction of protein and lipid components of erythrocyte membranes and also in photohemolysis of erythrocytes sensitized by chlorine e 6 were studied. It was found that 1O2 plays the dominant role in these processes, but contribution of other AOF, O2- in particular, can not be fully excluded.

[Characteristics of complex-formation of chlorine e6 with human and bovine serum albumins].

Pigment-protein complexes of chlorin e6 (Chl e6) with human (HSA) and bovine serum albumines (BSA) have been investigated by spectral-luminescent methods. Fluorescence quenching of tryptophan residues caused by the inductive-resonance energy transfer to pigment molecules and the rise of the polarization degree of Chl e6 emission were observed upon incorporation of Chl e6 in the protein globula. The obtained data on spectral-energetic parameters of protein tryptophanyls and Chl e6 permitted us to calculate the energy transfer critical distances R0 in complexes of Chl e6 with HSA (R0 = 32 A) and BSA (R0 = 35A).

[Photodynamic effect of chlorine e6 on erythrocyte membranes].

Photodestruction of erythrocyte membranes sensitized by water soluble chlorophyll derivative chlorine e6 (Chl e6) was studied. It has been determined that light irradiation of erythrocyte ghosts with wave length lambda-660 nm in the presence of Chl e6 caused in protein and lipid components of the membrane deep destructive changes which were expressed in cross-linking of the membrane polypeptides and accumulating in the membrane products of peroxidation of unsaturated fatty acids residues, in phospholipids mainly. It has been shown that these processes were realized only in the presence of molecular oxygen and consequently possess pure photodynamic character.

[Photosensitization by chlorine and porphyrin causing structural damage of erythrocytes].

Kinetics of hemolysis of human erythrocytes photosensitized by porphyrin and chlorin derivatives was investigated by small angle light scattering method. The compounds used were arranged in the following order of photosensitizing activity decrease: ethylendiamide of chlorine e6, chlorine e6 dimethylester chlorine e6 haematoporphyrin diacetate tetracarboxyphenylporphyn. The substances having a greater number of binding sites with liposomes (chlorine e6 dimethylester) or with albumin (ethylendiamide of chlorine e6) showed the greatest photohemolytic activity.

[Erythrocyte photohemolysis sensitized by chlorin e6].

Hemolysis of human erythrocytes photosensitized by chlorophyll derivative--chlorin e6 has been studied. This process was found to be oxygen-dependent. High photodynamic activity of chlorin e6 is explained both by its specific binding with cells and by its photophysics parameters.

[Mixed aggregation of pigments with participation of bacteriochlorophyll].

In binar mixture of solvents (dioxane--water, 1 : 4) the spectral-luminescent investigation of the regularities of mixed association and the energetic interaction between molecules of bacteriochlorophyll (BChl) and its analogs (chlorophyll a--Chl, protochlorophyll--PChl, 4-vinyl-protochlorophyll--4VPChl) under variation of donor-acceptor ratio (0,001 less than or equal to CD/CA less than or equal to 1) in the polymer complex was conducted. The essential role of the elementary cell structure of the mixed associate was discovered: the associate of individual BChl did not possess measurable fluorescence whereas the introduction of PChl, 4VPChl and Chl admixture (approximately greater than 1%) into BChl aggregate resulted in the appearance of a BChl fluorescent ability. It was suggested that admixture and BChl molecules formed dimer cells in which the excitation nonradiative deactivation probability was strongly decreased in comparison with individual BChl aggregate.

[Spectral-luminescent properties of separate aggregated forms of pigments in solutions].

The aggregated forms of protochlorophyll a (PChl), 4-vinyl-protochlorophyll a (4VPChl) and chlorophyll a (Chl) in binar mixtures of dioxane-water was investigated. The aggregates are oligomer particles of pigment molecules having considerable degrees of fluorescence polarisation which points to their ordered structure. Two types of fluorescent associates I and II have been discovered.

[Mechanism of photoregeneration of reduced porphyrin in the presence of oxygen].

Photooxidation of reduced forms of porphyrines (IIH2) was studied. It has been shown that photooxidation of IIH2 is sensitized by initial porphyrine formed in the course of the reaction. Singlet oxygen serves as the basic oxidizer.

[Intermediate reduction products of porphyrins and their structure].

It was shown on the basis of NMR-H spectra that the addition of proton to dianions of Zn-octaethylchlorine, Zn-octaethylporphin, and Zn-monoasaethioporphyrin results in the formation of products with the structure of alpha-dihydroflorine, alpha-florine, and gamma-florine respectively. This indicates that electron density greatly increases when the anions are formed in the centres which had a decreased density in the initial molecule.

[Relationship between chlorophyll concentration and the energy reaction between protochlorophyll and chlorophyll in mixed associations].

In the paper results are presented of investigation of protochlorophyll (PChl) and chlorophyll (Chl) mixed associations and of interaction between them within the polymer molecular complex, which forms in mixture of water-dioxane (1 : 4). The initial PChl concentration in all solutions was constant (CPChl = 1 . 10(-5) m/l), and Chl concentration varied from 1.

[Migration of electron excitation energy in mixed associates of chlorophyll and its derivatives].

The intracomplex migration is investigated of electron excitation energy between molecules which are a part of a mixed associate. Weakly fluorescent and nonfluorescent associates of chlorophyll and its analogues as well as of bacteriochlorophyll and neoxanthine have been used as donors and acceptors. The migration of excitation energy with variation of quantum yield of donor emission from 5-10(-3) to less than or equal to 10(-4) and also with very weak overlapping of luminescence and absorption spectra for the pair D leads to A is experimentally discovered by luminescence excitation spectra of mixed pigment aggregates.

[Mechanism of photooxidation of porphyrins with oxygen].

Dependence of quantum yield of porphyrines photooxidation with oxygen on their concentration has been shown. Sensitized by some porphyrines oxidation of other ones with oxygen has been studied in relation to concentration, intensity and wave length of absorbed light, quantum yield, interconversion and life time of the molecules in triplet state. Common mechanism for direct and sensitized photooxidation has been suggested.